NMR diagnosis of pseudo-scalar superconductivity in 3D Dirac materials

Recently observed 4π periodic Andreev bound states in three dimensional Dirac materials are attributed to convnetional superconducting pairing. Our alternative explanation in terms of a novel form of parity breaking pseudo-scalar superconducting order can be sharply diagnosed by nuclear magnetic resonance (NMR) relaxation rate. The left-right symmetry breaking of the pseudo-scalar superconductivity can be directly probed as an anti-peak structure below TC in sharp contrast to the conventional Hebel-Slichter peak.